Boston’s Daniel Nava pumps his fist while rounding the bases after hitting a three-run homer during the seventh inning of Monday’s victory over the Baltimore Orioles in Boston.

BOSTON — A second brilliant start by Clay Buchholz. A clutch homer by Daniel Nava. Another flawless fielding performance by the Boston Red Sox.

The fans at Fenway Park saw for the first time what all the excitement is about when they watched the surprising Red Sox beat the Baltimore Orioles 3-1 in Boston’s home opener on Monday.

“This team is growing in confidence by the day,” first-year Red Sox manager John Farrell said.

Buchholz (2-0) allowed three hits in seven shutout innings, Nava hit a three-run homer in the seventh off Wei-Yin Chen (0-1) and the first-place Red Sox improved to 5-2 for their best start in seven years.

Last year, they lost five of their first seven games and finished last at 69-93, and in 2011 they started 1-6 and missed the playoffs with a September collapse.

So winning Monday after taking two of three road games against both the New York Yankees and the Toronto Blue Jays “is a lot better than starting 2-9, or whatever it was last year and the year before. We’ve got an awesome group of guys,” Buchholz said. “It’s easier to come to the ballpark and be in high spirits, in good spirits about it whenever your team is winning.”

The Red Sox won their ninth straight home opener a day after Jon Lester pitched seven innings in a 13-0 win in Toronto. Boston pitchers had 18 consecutive scoreless innings before Adam Jones hit his first homer of the year with one out in the ninth off Joel Hanrahan, who finished for the save.

Boston’s new closer is perfect in three save tries this season.

The Red Sox haven’t committed an error in any of their seven games, their longest season-opening errorless streak.

Nava broke open a scoreless duel with his second homer in two days. He hit a shot over the Green Monster in left after Dustin Pedroia singled and took third on a double by Mike Napoli.

“It was special just because it was opening day,” Nava said. “I wasn’t trying to hit a home run. It just worked out like that but to contribute and get us a lead in a tight game after Buck pitched well is something that I think anyone who stepped in the box in (that) situation was looking to do.”

Buchholz gave up three walks and struck out eight. Last Wednesday he allowed one run in seven innings in a 7-4 win over the Yankees.

“He had very good stuff,” said Farrell, who took over after Bobby Valentine was fired following one season as Boston’s manager. “You can’t say enough (about) what Clay did for us. The way Chen was pitching, a classic pitchers’ duel, and one swing of the bat becomes the difference.”

Andrew Bailey blanked the Orioles in the eighth before Hanrahan, acquired from the Pittsburgh Pirates in the offseason, made his Fenway debut.

“We might spend all day tomorrow crying as a team, holding each other’s hands, spend all day walking through the Prudential Center (in Boston) crying,” outfielder Adam Jones said sarcastically after Baltimore fell to 3-4. “We’re playing good baseball. We’ve got 155 games to go; a lot of games to go.”

Buchholz allowed the first batter to reach base in four innings but only one runner advanced to second.

“I actually felt better pitching out of the stretch,” Buchholz said. “I felt like the tempo was better.”

The Orioles put the leadoff runners at first in the first two innings, Nate McLouth with a single and Chris Davis with a walk, but neither moved up. With two outs in the third, singles by Manny Machado and Nick Markakis put runners at first and second before Jones took a third strike.

Davis led off the fourth with a walk but was forced out at second on a grounder by Matt Wieters. J.J. Hardy then grounded into a double play, ending the inning.

In the fifth, McLouth drew a two-out walk, but Machado flied out to right fielder Shane Victorino. Buchholz finally pitched a perfect inning in the sixth when Markakis grounded to first, Jones flied to right and Davis struck out looking. Buchholz walked Wieters leading off the seventh then retired the next three batters, striking out two and completing an impressive 113-pitch performance.

“We didn’t do much offensively,” Orioles manager Buck Showalter said. “Seven games into the season, no one’s concerned.”

The Red Sox managed just four runners in the first six innings on two singles and two walks but none got past first base.

Nava walked with two outs in the second before Johnny Gomes popped out to second baseman Ryan Flaherty. Victorino started the fourth with a single but was caught stealing. Pedroia then walked before Napoli grounded into a double play.

Nava then singled with one out in the fifth, but Chen struck out Gomes and got David Ross to ground out to Flaherty.

NOTES: Boston RHP John Lackey is expected to miss his next start, scheduled for Friday, with inflammation in his right biceps. He walked off the mound with pain in his right arm in the fifth inning of Boston’s 5-0 loss at the Toronto Blue Jays, his first start after elbow surgery that sidelined him all last season. ... After an off day Tuesday, Jake Arrieta (0-0) pitches for the Orioles on Wednesday night against Ryan Dempster (0-1). ... Red Sox rookie LF Jackie Bradley Jr., got the day off after batting .143 in the first six games following an outstanding spring training that earned him a spot on the opening-day roster. ... The National Anthem was sung by the Jimmy Fund Chorus. This is the 60th year in which the Jimmy Fund, associated with the Dana-Farber Cancer Institute, has been the Red Sox official charity. ... Former astronaut Edwin “Buzz” Aldrin, the second person to walk on the Moon, attended the game.